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Techniques of Absorption Spectroscopy. UV-vis and Infrared spectroscopy deals with absorption of radiation-- detect attenuation of beam by sample at detector. radiation source. transmitted radiation. detector. Frequency selector. Sample. I. I o. T = I/I o. A = -log 10 (T).

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  1. Techniques of Absorption Spectroscopy UV-vis and Infrared spectroscopy deals with absorption of radiation--detect attenuation of beam by sample at detector radiation source transmitted radiation detector Frequency selector Sample I Io T = I/Io A = -log10(T) Dispersive spectrometers measure transmission as a function of frequency (wavelength) - sequentially--same as typical CD Interferometricspectrometers measure intensity as a function of mirror position, all frequencies simultaneously--Multiplex advantage

  2. Dispersive and FT-NIR Spectrometer Wolfram-Lampe(Tungsten lamp); Gitter(Grating); Spalt(Slit); Lichtquelle(Light source); Spiegel(Mirror), Detektor(Detector); Probe(Sample), Spektrum(Spectrum)

  3. Sample Detector: PMT or CCD for multiplex Lens Filter Single, double or triple monochromator Laser Dispersive Fluorescence or Raman • -use filter or double monochromator to eliminate the intense Rayleigh scattered & reflected light • --Fluorescence not big problem • Raman typically 108 weaker than excitation • Disperse the light onto a detector to generate a spectrum Polarizer Detect intensity, I, against zero background--ideal

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